The present invention relates to a controlling device for a laundry washing machine of a type in which clothes are washed through spraying washing liquid onto the laundry or clothes.
In U.S. patent application Ser. No. 677,302, filed Dec. 3, 1984, and now U.S. Pat. No. 4,580,421, there is disclosed a laundry washing machine of the above type which includes a washing tub, a laundry containing drum and a collector for the wash liquor or liquid positioned beneath and connected with the washing tub, the collector being so shaped as to contain at least a filtering element, an electric heating element and a thermostatic sensor for respectively filtering, heating and sensing the temperature of the wash liquor.
The wash liquor collector is connected both with outlet piping of the washing machine through a usual drain pump, and with the wash tub through a further piping system and an electric circulating pump, which can be either separate from or on the same axis with the drain pump, the electric circulating pump being provided with a suction opening connected with the wash liquor collector as well as a delivery opening connected with the further piping system.
Such a machine allows therefor for performing both "intensive" and "delicate" washing programs of a traditional type for washing heavily soiled clothes at normal levels of the wash liquor in the tub, while keeping the circulating pump switched off for the entire duration of such washing programs, as well as "intensive" washing programs for laundering not so heavily soiled clothes at lower levels of the wash liquor in the tub and switching on the circulating pump during certain periods during such washing programs in such a way that the wash liquor is repeatedly circulated from the collector into the tub through the piping system and is directly sprayed onto the clothes.
In particular, these special "intensive" washing programs are used to wash not so heavily soiled cottons and/or heat-resistant synthetics by filling the wash liquor into the collector at different reduced levels according to the actual wash load in the drum.
Such special programs do not include pre-soak or pre-wash cycles of the type usually available in traditional "intensive" to "delicate" washing programs, but only a suitable sequence of washing steps in which the circulating pump is constantly kept under a switched-on condition and the wash liquor is heated up to maximum temperatures of approximately 90.degree. C., while the drum is rotated both at wash speed with a reversing action, and at spin-extraction speed for shorter time spans than at the regular wash speed. At the end of the actual washing process, the wash liquor is discharged under a switched-off condition of the recirculating pump. Thereafter, a sequence of regular rinse cycles is performed in a traditional way. As a result, these "intensive" washing programs, owing to the reduced levels of wash liquor used in the tub, can be performed with substantial savings of water, detergents and energy as compared with traditional programs.
However, while operating satisfactorily and reliably, such a washing machine has some drawbacks.
A first drawback involves limitations in the applicability of washing programs involving reduced levels of the wash liquor in the tub. In particular, such programs are not applicable to the washing of clothes with special kinds of soils, such as some proteinic or organic soils (blood, cocoa, milk, etc.), mud and similar soils, which require that the wash liquor be heated up to low temperatures (approximately 40.degree. C.) and duly kept to such temperature values for fixed periods of time in order to prevent soil from fixing onto the clothes. As a matter of fact, in such a case, due to the reduced amount of water that is being filled into the tub, the wash liquor would be heated up very quickly, thus preventing the lower temperature values from being maintained for a suitable period of time as required for best washing results. In other words, clothes with such particular soils would be washed at higher than optimal temperatures and this would inevitably lead to unsatisfactory washing results.
Furthermore, the above mentioned washing programs would only give satisfactory washing results when laundering cottons and/or heat-resistant synthetics which are not so heavily soiled and do not, therefore, require a pre-soak or pre-wash cycle in order to completely remove soil.
Also, such washing programs would not lead to satisfactory results even when laundering clothes of the type mentioned above if they are heavily soiled and therefore require a preliminary soak or pre-wash cycle for adequate soil removal, since the programs are not designed to include such a pre-soak or pre-wash cycle.
Further drawbacks in the use of this washing machine derive from the absence of suitable safety devices to check both the filtering element for efficiency and the heating element for safe operation, i.e. to make sure that the latter only operates when actually flooded with wash liquor. As a matter of fact, in the first case, since the filtering element is designed to retain soil particles from the wash liquor being circulated from the appropriate collector to the machine tube through the proper recirculation pipe, there is the actual need for constantly checking the filtering element in order to immediately sense an irregular condition, e.g. clogging, and to enable the user to clean or possibly replace the filtering element for ensuring a constantly effective circulation of the wash liquor. In the second case, the heating element must always be flooded, i.e. submerged in the wash liquor, to ensure its correct and safe operation, or else it will overheat to excessive temperature values, thereby risking damage to the element itself and the washing machine.